During communication, packet loss associated with lowering of the network quality causes defects such as deterioration and freeze of video and disturbance of audio. Therefore, there is a need for quality control (QoS: Quality of Service) by which the quality of video and audio transmitted via a network is kept high. The QoS mechanism includes, for example, a packet retransmission function (ARQ: Automatic Repeat reQuest) and a forward error correction function (FEC: Forward Error Correction).
For example, Patent Literature 1 describes a technology called hybrid ARQ combining the ARQ with the FEC. In this technology, only packets, which were not able to be restored by the FEC, are retransmitted by the ARQ.